Broadleaf Crops

Hans Kandel NDSU Extension Agronomist e-mail Hans.Kandel at NDSU.edu

Cover Crops

There are many options for cover crops on the farm. The first option is to use a species in the grass family (oats, barley, wheat, sorghum, etc). The second option is to use a broadleaf crop (field pea, clovers, turnip, other brassica species, and others) and the third option is to use a crop mixture using different species. The grasses are relatively inexpensive, can be broadcast or drilled, take up nitrogen from the soil, promote mycorrhiza growth in the soil, and broadleaf herbicides can be used if necessary to control some weeds. The advantage of using a legume is that it can biologically fix Nitrogen. The legume biomass has about 4% Nitrogen. Not all of this Nitrogen is biologically fixed as some is taken up from the soil. For the best results field pea and other species with large seeds need to be planted with a drill or planter and not broadcasted. Other small seeded legumes and other crop species can be broadcasted and harrowed in. However using a seeder will give better results. A cocktail of different species is popular in certain areas of the state.

The benefit of cocktails is that they contain many different species and depending on the growing conditions the most adapted species will dominate in the mixture. Warm and cool season crops can be mixed as well as broadleaf and grass species. There is not one mixture that fits all conditions. Many different mixtures can work. It will depend on the main objective of the producer. If fixing nitrogen is important the mixture should be a mix of legumes with a small percentage of other crops. If for instance late fall grazing is an objective, possibly turnips and radishes could be a component of the mixture. The more diverse the mixture the more likely it is that some of the component species will do well during the season. The cost of course needs to be considered. Weed control before seeding of a cocktail is important. A great resource for North Dakota is the “Cover Crop Chart” produced by the Northern Great Plains Research Laboratory ARS staff at Mandan.

Other considerations for acres which have not been seeded: use the area as acreage for seeding winter wheat in the fall, clean the rocks out of the field, or take the opportunity to install sub-surface drainage or improve surface drainage.

Cover Crops After Wheat

Before using cover crops in the cropping system, it is important to decide what the purpose is of the cover crop, forage crop, or cover crop mixture. Using a mixture of cover crops may allow producers to meet several goals simultaneously. Cover crop mixtures add more diversity, compete better with weeds, optimize nutrient cycling, and use the available moisture in a more efficient manner. Mellowing the soil and/or adding organic matter are usually the primary goals of growing a cover crop. Use of soil moisture by a cover crop, during the period after the main crop has been harvested, might be one of the objectives in a relatively wet year. However, in a dry year a cover crop may use soil moisture that otherwise possibly might be used by a crop during the next season.

In North Dakota spring wheat is seeded in the early spring and wheat is harvested at the end of July or early August. Winter wheat is typically harvested two weeks before spring wheat. The average first killing frost in the fall is around the 20th of September in central North Dakota. This period of time between wheat harvest and up until the first killing frost can be used for additional forage or biomass production. The key is the availability of sufficient soil moisture and or precipitation. If a mixture of more cold tolerant species is included in the cover crop mixture, the growing window may be extended well into October. During the last growing seasons, we compared three cover crop mixtures. In Fargo and Dickinson cover crops were seeded into fallow ground, to avoid volunteer wheat. In Fargo a wheat treatment was broadcasted to simulate volunteer grain. In Hettinger, in 2010, the cover crops were seeded into wheat stubble. The mixtures which included brassica species established well.

3There is no significant difference at P≤0.10, if at least one letter behind means is similar.

Near Fargo, mixture 3 was significantly better than mixture 1. The difference between the two mixtures in biomass yield is attributed to the presence of the brassica species (kale, turnip and radish). In Dickinson and Hettinger, mixture 2 (with the brassica species) was significantly better than mixture 1. The mixtures mentioned in this article (see Photo 1) are just examples to show that there are opportunities to capture sunlight in the fall and transform the energy into biomass. Radish and turnip have also performed well in other previous research. Many different mixtures of various species can be composed and this will most likely reduce the production risk. However, if there is not enough moisture to establish and sustain the cover crop, the biomass produced will be very low. In western North Dakota the risk of limited establishment tends to be due to the generally drier conditions (see low yield levels at Dickinson and Hettinger). If seeded directly into wheat stubble, volunteer wheat may compete with the seeded cover crop and volunteer wheat plants may have to be controlled.

Tile drainge

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NDSU Extension Offers Crop and Pest Report

Each season brings new challenges and pest problems in crop production. To help, the North Dakota State University Extension Service is offering a “Crop and Pest Report” newsletter.

It will keep producers and others informed and prepared on how to effectively manage any problem. The newsletter is a weekly series of updates on crop, soil, insect, disease, horticultural and weed conditions. Each issue contains

valuable information about insect and disease problems, pest alerts, integrated pest management strategies, pesticide updates, agronomy and fertility issues, horticulture problems, reports from the NDSU Plant Diagnostic Laboratory, important Extension meetings and a weather outlook.Local reports also are included on agronomic and pest issues, plus crop development from agronomists at the Research Extension Centers across the state.

Subscribers will have the option of receiving the newsletter by mail or electronically in a color PDF format. To subscribe for the free e-mail or mailed version of the report, visit the crop and pest report website .